Emma Hazlett, 72, jumped out of bed and threw open the curtains. Just a few feet away, her neighbor's house was ablaze, set on fire when the plane slammed into the ground, burst into flames and cartwheeled over the roof.

"The ground rattled," Hazlett recalled. "Boom! Boom! Boom!"

Investigators said the plane was flying no more than 50 feet above the ground when it clipped a tall oak tree at 6:30 a.m. Sunday and crashed.

Remarkably, the house that caught fire was the only unoccupied one on the block, which is in a densely populated neighborhood in east Zephyrhills.

The plane's two occupants, a male pilot and a female passenger, were killed on impact.

Investigators were working late Sunday to identify them and learn more about the flight of the four-seat, Grumman Tiger aircraft. There were no injuries on the ground.

Many of the clues usually available to investigators burned in the wreckage. It was unclear late Sunday who owned the plane, where the flight originated or whether the pilot was trying to land at Zephyrhills Municipal Airport, just south of the crash site.

Officials said the plane was flying south, in the direction of the airport.

The aluminum shell of the plane melted in the fire, leaving no trace of a tail number or a flight log book. All investigators had to go on was an identification number they found on the engine block.

The pilot filed no flight plans, said Zephyrhills Police Sgt. Larry Davidson. Officials at the Zephyrhills airport reported no communications with the plane. Because of poor visibility, the airport was closed to landings, even for pilots flying with instruments.

"It was too foggy to land, much less fly," said airport manager Jim Werme.

Authorities were at a loss to explain why the pilot was flying at such a low altitude.

"It's baffling," Davidson said. "If he wasn't having engine problems, he had no idea where he was."

An investigator with the National Transportation Safety Board arrived from Atlanta to investigate.

The thankful and the curious gathered at the scene throughout the day, tracing the plane's final moments. They pointed to the broken tree branches and scattered airplane parts that stretched a block north of the crash. But their eyes always returned to the charred house at 39444 Eighth Ave., the one with the hole in the roof and the blackened wreckage in the back yard.

Property records show the single-story, white-brick house is owned by Helen Walters of Rochester, N.Y., who could not be reached Sunday. Neighbors said Walters rented the house part of each year, but the place has been vacant for months.

Especially thankful was Bob McGill. After striking the first tree, the damaged plane passed directly over McGill's house, barely missing his roof, investigators said. The plane then clipped a second tree, in McGill's front yard, and slammed into the ground across the street.

"There but for the grace of God...," said McGill, 58, who was sleeping when he heard what he thought was thunder. In his back yard, beside his pool, was a large portion of a wing.